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Finley Robinson Porter’s Horizontally Opposed Dual Four Cylinder Engines

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  •          Plan-view of the horizontally opposed dual four-cylinder engines.

Horizontally-opposed dual four-cylinder engines with common rotary valves, certainly is a mouthful. But that is exactly what Finley Robinson Porter had finished designing only a little over a year after he left Mercer, as the Chief Engineer where he designed the legendary T-head Raceabout. This pair of engines was intended for aircraft use, and each was to be equipped with a propellor. At this point, it is unknown if this project ever went past the drawing stage, but it certainly is interesting to study his work.

We were fortunate to be able to talk with Porter’s Great Granddaughter recently and learned of this concept and its drawings. After studying them we are amazed by the vision that this man had and his ability to be able to see this concept through to its final design and drawings. It came right on the heels of the exceptional F.R.P. car he designed and built with a s.o.h.c. 454-c.i.d. four-cylinder engine that was right on the cutting edge at the time.

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  • Sectional views of the end and center of the engines.

Just above at the top is a cross-sectioned end view of a pair of cylinders, and it shows one of the rotary valves located top and bottom on ball bearings. The intake charge enters the valve at (2) on the middle bottom and exhausts out of the top of it. The valve supply chamber (4) communicates with the feed (1) from the intake manifold and has opposed cylinder supply ports (6 and 7 –  see photo at the top of the post) opening through the face of the valve.

The exhaust chamber (5) communicates with the upwardly extended tubular portion (2) that also has opposed exhaust ports (8 and 9 – see photo at the top of the post) opening through the face of the valve. The rotary valve is tapered and is smaller at the bottom than at the top. The fuel supply for the cylinders is drawn in through the bottom of the valve, and the exhaust gases are discharged through the top of the valve.

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  • Detail views of the gear drives, a valve and the combustion chamber.

The two detail photos above show more of the construction. The left-hand drawing shows the intermediate gear (48) that is driven by a gear on the two joined-driveshafts (38). It in turn drives shaft (46) that operates the four rotary valves and gear and shaft (55) that drives the magneto on the left (52) and the water pump on the right (53). The right-hand drawing shows the details of the gears (49 and 50) that turn the rotary valve and also shows the combustion chamber. The updraft intake manifold (70) can be seen in the bottom center photo.

8 responses to “Finley Robinson Porter’s Horizontally Opposed Dual Four Cylinder Engines

  1. Very interesting and advanced design. Having propeller swing determined more or less by the engine stroke seems to be an obvious weakness, perhaps indicating not much exposure to aircraft practice and technology. Not knowing that prop efficiency is generally increased as a prop diameter increases is more than a minor oversight. this design was probably was never built for any aircraft use.

    With a proper geartrain this would have made a interesting automobile engine. However Eugène Brillié was there first with the Gobron Brillié and Louis Rigolly the first to 100 mph in Ostend on July 21, 1904 in a Gobron-Brillié.

    Mystery Foto #7 Solved: Driver Louis Rigolly in a Gobron-Brillié Racer

      • Yes to the single crankshaft engine. Also not a horizontal engine like FRP’s.

        Might want to think a little about how that prop timing would work as each prop attempted to swinging past the opposite prop hub…

        Functional with one prop, but more parts needed for that.

        • I was thinking of props no longer than what was needed for clearance at each hub. Of course if anything when wrong with either prop or the bottom end of an engine it would probably take out both props.

          • I didn’t say what I intended to “Having propeller swing determined more or less by the engine stroke” should have been something like

            Without some sort of additional drive mechanism the prop swing of a direct coupled prop would be essentially limited to the sum of 1/2 the stroke + rod length + piston height.

  2. David this is a very early design concept of the engine layout Junkers used it in aircraft was also used in massive marine motors and now it is being revived in a new single crank motor for the future.
    Cheers now
    Jeff Marshall

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